1. Field of the Invention
This invention relates to a process and system for fluid distribution from a principal intelligence and fluid distribution center, having overall summary control of an entire system, to multiple users through distributed intelligence sub-centers having control of a portion of the system. Intelligence transmission from individual user valves and meters to the distributed intelligence sub-centers and from the distributed intelligence sub-centers to the principal intelligence and fluid distribution center is achieved in conjunction with the piping by means such as wires within the cavity, wires imbedded in the structure of the piping, wires along the exterior of the piping, fiber optics, or acoustic, electromagnetic or optical methods through the piping itself. The distributed intelligence sub-centers are computers having data computing, analyzing, decision making, and direction capability to provide for their area flow control, leak detection, pipe condition assessment, user meter reading, pipeline locator signals, and robot control for locating leaks, providing leak locator signals, flow control, and pipeline repair or cleaning. The process of this invention provides a total system approach to improved safety and reduced operating costs for distribution systems and is particularly well suited for underground distribution of natural gas services.
2. Description of the Prior Art
Fluid distribution systems, such as natural gas distribution to residences and businesses, have generally been by underground piping from a central distribution center through service pipes to the individual user and through valves and meters at the user end of the service pipeline. Such systems require reading meters at the individual user location and are generally not monitored with respect to fluid theft or leakage. Further, to adjust the flow or to turn on or to turn off individual user service requires manual operation at the user location. Generally fluid flow control is governed by valves at the user service lines and at the central distribution center, valves in supply lines, if any, frequently being manual underground valves. Particularly when the fluid is gas, the user service lines or the supply lines are difficult to locate, especially by above-ground techniques. Damage to the service and the supply lines is greatly increased by the present difficulty in ascertaining their location.
U.S. Pat. No. 4,200,911 teaches control of flow rate and fluid pressure in a pipeline network by actual fluid consumption measurement to establish a demand pattern. The predicted demand pattern for each area is ascertained by comparing characteristics of each area with those of other areas having standard demand patterns and the pumps and valves are controlled on the basis of the predicted demand patterns. This system, however, cannot provide for unusual demands or emergencies.
U.S. Pat. No. 3,874,222 teaches a leak detection and location system for a pipeline carrying fluids at different than ambient temperatures by placement of temperature sensing means to the exterior of the pipeline. The temperature sensors are located in a trough to the exterior of a liquid pipeline and provide a signal to a central monitoring station when other than ambient temperature is detected. A wide variety of sonic leak detectors have been used for fluid lines as described in U.S. Pat. Nos. 4,083,229; 3,223,194; 3,055,209; 3,264,864, but none of these systems described in these patents provide the desired ease and sensitivity of leak detection for underground gas leaks.
Various methods have been used in the art for pipeline flow restriction such as exemplified by U.S. Pat. No. 4,291,727 and the references cited therein. However, the flow restrictor of the U.S. Pat. No. 4,291,727 requires, in the case of an underground pipe, that the pipe be exposed and a saddle device attached for interior access at the point where flow restriction or stoppage is desired.
The use of pigging devices has been known for cleaning gas collection lines and various methods have been used for monitoring the pigs in the pipelines as taught by U.S. Pat. No. 3,384,512.
Various methods for fluid flow control and fluid valve control have been used based upon pressure sensing as taught in U.S. Pat. No. 3,846,706; electronic measurement of liquid flow utilizing level and velocity detectors as taught by U.S. Pat. No. 4,202,211; electromagnetically controlled single water pipe flow with temperature control by mixing hot and cold for individual demands as taught by U.S. Pat. No. 2,908,017; control of fluid injection into the main stream of a system by a flow meter in the main stream as taught by U.S. Pat. No. 4,007,755; and various specific means of fluid valve control as taught by U.S. Pat. No. 3,946,287; and fiber optic control as taught by U.S. Pat. No. 4,306,314.